Generally, Giant Magnet Resistance (GMR) elements for detecting presence or absence of magnetism are widely known. The phenomenon that electric resistivity fluctuates when a magnetic field is applied is called magnetoresistive effect. Although its change rate of a common substance would be several percent, the change rate of such GMR element reaches several tens of percent. For this reason, the GMR elements are widely used for heads of hard disks.
FIG. 1 is a perspective view illustrative of the operation principle of a conventional GMR element, and FIG. 2 is a partial cross-sectional view of FIG. 1. In the drawings, a reference numeral 1 denotes an antiferromagnetic layer, a reference numeral 2 denotes a pinned layer (fixed layer), a reference numeral 3 denotes a Cu layer (spacer layer), and a reference numeral 4 denotes a free layer (free rotation layer). A magnetization direction of a magnetic material changes electronic spin scattering, and changes a resistance. In other words, it is represented by ΔR=(RAP−RP) RP (where RAP: when magnetization directions on upper and lower sides are not parallel, and RP: when magnetization directions on upper and lower sides are parallel).
As for the magnetic moment of the fixed layer 2, the direction is fixed by magnetic coupling with the antiferromagnetic layer 1. When the direction of the magnetic moment of the magnetization free rotation layer 4 changes due to leakage field, the resistance which a current flowing through the Cu layer 3 receives changes, and a change of the leakage field can be detected.
FIG. 3 is a schematic diagram illustrative of a laminate structure of the conventional GMR element. In the drawing, a reference numeral 11 denotes an insulating film, a reference numeral 12 denotes a free layer (free rotation layer), a reference numeral 13 denotes a conductive layer, a reference numeral 14 denotes a pinned layer (fixed layer), a reference numeral 15 denotes an antiferromagnetic layer, and a reference numeral 16 denotes an insulating film. The free layer (free rotation layer) 12 is a layer in which a magnetization direction rotates freely, and is made of NiFe or CoFe/NiFe. The conductive layer 13 is a layer in which a current flows and the spin scattering occurs, and is made of Cu. The pinned layer (fixed layer) 14 is a layer in which a magnetization direction is fixed in a fixed direction, and is made of CoFe or CoFe/Ru/CoFe. The antiferromagnetic layer 15 is a layer for fixing the magnetization direction of the pinned layer 14, and is made of PtMn or IrMn. The insulating films 11 and 16 are made of Ta, Cr, NiFeCr, or AlO. The pinned layer may use a self-bias structure instead of the antiferromagnetic layer.
For example, a system described in PTL 1 relates to a magnetic recording system using a GMR element, and is a spin-valve magnetoresistance (MR) sensor including a fixed ferromagnetic layer which has been improved so that the magnetostatic coupling of a free ferromagnetic layer is the minimum. In FIG. 4 of PLT 1, a lamination structure including the free ferromagnetic layer and a fixed ferromagnetic layer is illustrated.
In addition, a magnetic sensor using a Hall device is proposed as a terrestrial magnetism sensor for detecting a three-dimensional magnetic field vector. This type of Hall device can detect a magnetic field in a direction perpendicular to an element face, and can detect a magnetic field in Z direction when the element is arranged on the flat surface. For example, PTL 2 describes that Hall devices are arranged in a cross shape, i.e. on the upper and lower sides, and right and left sides with respect to a symmetry center under a circular magnetic convergence plate. By utilizing a magnetic field in a horizontal direction that is converted into a Z-axis direction at an end of the magnetic convergence plate, not only the Z direction which is a magnetic sensitivity direction of a Hall device of the magnetic field but also the horizontal direction are detected, so that the magnetic fields in X-, Y-, and Z-axis directions can be detected on the identical substrate.
In addition, for example, a sensor described in PTL 3 relates to a magnetic sensor including magnetoresistance effect elements arranged so as to cross in three dimensional directions on a single substrate. Its description is made for a magnetic sensor using the magnetoresistance element including a pinned layer and a free layer, in particular, a magnetic sensor with high sensitivity measuring a magnetic field in a direction perpendicular to a surface of the magnetic sensor. PTL 3 proposes that X-, Y-, and Z magnetic fields are detectable on the same substrate, by performing vector decomposition for the Z magnetic field applied in the vertical direction which is originally undetectable, by forming the magnetic sensor with a magnetoresistance element detecting a horizontal magnetic field on an oblique slope.
In addition, for example, what is described in PTL 4 relates to a three-axis magnetic sensor having a high sensitivity for azimuth detection, being compact, and having excellent mass production nature. The magnetic sensor includes: a two-axis magnetic sensor unit for detecting terrestrial magnetism components in the two-axis directions (X and Y axes) which are set parallel to the substrate surface and perpendicular to each other; and a magnetic member concentrating a magnetic field in the perpendicular direction (Z axis) to a surface including the two axes and arranged on the two-axis magnetic sensor unit. Proposed is that coils are formed on a magnetoresistance element, and the direction of a magnetic field is converted by a magnetic body with 4-fold rotational symmetry with a magnetization direction being controlled by a magnetic field occurred by a current flowing through the coils, so that the X-, Y-, and Z magnetic fields can be detected on the identical substrate.
In addition, for example, an element described in PTL 5 relates to a giant magnet resistance element which receives few influence of a direction of a magnetic field, and which can detect a magnitude of a magnetic field with sufficient accuracy. The GMR element is formed by a pattern with one polygonal line against a GMR chip, and the GMR chip is implemented on the substrate.